When Olympus Has Fallen star Aaron Eckhart needed to know what if felt like to be physically attacked by a terrorist he didn’t have to use his imagination.

Jones, a counter-terrorism expert, not only advised actors on worst-case scenarios for the new film but helped shape the movie’s abduction of the Commander in Chief. Olympus Has Fallen, opening March 22, chronicles an all-out assault on the White House by North Korean terrorists willing to do whatever it takes to change the country’s foreign policy regarding South Korea.

Director Antoine Fuqua (Shooter) wanted to get as many details about such a scenario right, and so the film’s script ended up on Jones’ desk for review. Jones did his best to make sure the critical sequence played out in as realistic a fashion as feasible for a big-budget adventure.

Jones, who was on set for all but the first day of shooting, says he ended up changing five items in the script to make it more honest to what could actually happen given his background.

“[Fuqua] didn’t want a Die Hard thing where you’re running across glass and fighting six guys,” says Jones, who says he’s been stabbed in the line of duty. Instead, Fuqua wanted to know what the characters would endure, both physically and mentally, in such situations.

The film marks Jones’ first exposure to movie making, but he instantly appreciated the overall tone the director wanted for the project.

“He wanted it as real as real can get, but he also wanted the Secret Service to look like the heroes they are … how dedicated they are to the constitution of the United States,” he says.That approach certainly applied to star Gerard Butler, who plays a tormented Secret Service agent who gets a second chance when the president is captured. The actor worked with fight coordinators into the wee hours of the night to nail the action sequences, Jones reports.

“We really wanted to honor these men and women of the Secret Service,” he says.

Jones says he wouldn’t mind consulting on a second Hollywood feature, particularly if Fuqua was the one behind the camera. But while he’s led a colorful life in service to his country you won’t be reading any of his exploits on the printed page–or seeing them on the big screen. He’s honor bound to take those memories with him to the grave.

“I love my country and I will not break my word that I gave,” he says.